topical media & game development

topical media & game development

[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

#Key.ax

#Key.ax [swf] flex


  // ActionScript file
  // @ax-Key.as
  package {
     
      import flash.display.Stage;
      import flash.events.Event;
      import flash.events.@fileboardEvent;

The @ax-Key class recreates functionality of @ax-Key.isDown of ActionScript 1 and 2. Before using @ax-Key.isDown, you first need to initialize the @ax-Key class with a reference to the stage using its @ax-Key.initialize() method. For key codes use the flash.ui.@fileboard class. Usage: @ax-Key.initialize(stage); if (@ax-Key.isDown(@fileboard.LEFT)) { // Left key is being pressed }


  
      public class @ax-Key {
         
          private static var initialized:Boolean = false;  // marks whether or not the class has been initialized
          private static var keysDown:Object = new Object();  // stores key codes of all keys pressed

Initializes the key class creating assigning event handlers to capture necessary key events from the stage


  
          public static function initialize(stage:Stage) {
              if (!initialized) {
                  // assign listeners for key presses and deactivation of the player
                  stage.addEventListener(@fileboardEvent.KEY_DOWN, keyPressed);
                  stage.addEventListener(@fileboardEvent.KEY_UP, keyReleased);
                  stage.addEventListener(Event.DEACTIVATE, clear@files);
                 
                  // mark initialization as true so redundant
                  // calls do not reassign the event handlers
                  initialized = true;
              }
          }

Returns true or false if the key represented by the keyCode passed is being pressed


  
          public static function isDown(keyCode:uint):Boolean {
              if (!initialized) {
                  // throw an error if isDown is used
                  // prior to @ax-Key class initialization
                  throw new Error("@ax-Key class has yet been initialized.");
              }
              return Boolean(keyCode in keysDown);
          }

Event handler for capturing keys being pressed


  
          private static function keyPressed(event:@fileboardEvent):void {
              // create a property in keysDown with the name of the keyCode
              keysDown[event.keyCode] = true;
          }

Event handler for capturing keys being released


  
          private static function keyReleased(event:@fileboardEvent):void {
              if (event.keyCode in keysDown) {
                  // delete the property in keysDown if it exists
                  delete keysDown[event.keyCode];
              }
          }

Event handler for Flash Player deactivation


  
          private static function clear@files(event:Event):void {
              // clear all keys in keysDown since the player cannot
              // detect keys being pressed or released when not focused
              keysDown = new Object();
          }
      }
  }

[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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